Electronic piano having means responsive to the velocity of the action



A ril 26, 1966 J. MARKOWITZ ETAL ,2

ELECTRONIC PIANO HAVING MEANS RESPONSIVE TO THE VELOCITY OF THE ACTION Filed April 24, 1963 INVEN'TOKS- JEROME MARKOW/TZ MILTON/T NELSON BY [OW/N H. .S'T/PA/N M902 SM ATTORNEY United States Patent 3,248,470 ELECTRONIC PIANO HAVING MEANS RESPON- SIV E TO THE VELOCITY OF THE ACTION Jerome Markowitz, Allentown, Milton F. Nelson, Macungie, and Edwin H. Strain, Allentown, Pa., assignors to Allen Organ Company, Macungie, Pa., a corporation of Pennsylvania Filed Apr. 24, 1963, Ser. No. 275,380 16 Claims. (Cl. 841.1)

In general, this invention relates to a new and improved electronic musical apparatus utilizing electronic techniques for producing the sound of a conventional piano and/0r organ. More particularly, it is directed to an electronic piano which may be utilized with any of the known piano actions with the same degree of control as is presently possible with conventional pianos.

The conventional piano produces its characteristic tone by means of an action consisting of primarily mechanical levers by means of which a felt hammer can be caused to strike one or more taut steel strings with a wide range of velocity and force causing the strings to vibrate. These vibrations are transmitted to a sounding board for amplification. An extremely high order of control can be exerted on the amplitude and other tonal characteristics of the sound by a skilled performer. The wide range of amplitude results mainly from the construction of the mechanical linkage between the key which is struck by the performer and the felt hammer, and this led to the original name of the instrument, the pianoforte.

In the. past, electrification of pianos has fallen along certain conventional lines. That is, developments in the past have been directed to the electrical amplification of the sound produced by a piano. These techniques included utilizing the strings to excite, electromagnetic or electrostatic pickups, or by having the hammers strike vibrating reeds which produced output signals in accordance with their mode of vibration. However, these techniques produced pale imitations of the sound produced by a conventional piano and were therefore not acceptable except as novelty items.

In accordance with the teachings of the present invention, an electronic piano is disclosed which utilizes a conventional piano action plus electronic means for producing an electrical signal which when amplified and transduced by a suitable speaker will produce a piano-type tone. A piano constructed with the electronic means of the present invention resembles a conventional piano in respect to the keyboard and key action, but the strings and sounding board are replaced by electronic components.

Theelectronic means is operative from the felt hammer ofthe piano action to produce a signal in accordance with the velocity of the hammer. This is similar to operation of the strings of a conventional piano Each note on the piano scale is produced electronically with its amplitude dependent upon the force and velocity of the hammer. Since the art of electronic tone generation has reached a high degree of sophistication, it is possible to design a piano with selective dynamic variations which would enable it to match or better the sound of the finest conventional pianos presently in use. Further, this can be achieved with a unit which is considerably lighter and smaller in size than most of the conventional pianos.

Still further, by utilizing static electronic components,

the electronic piano need only be tuned in yearly intervals as opposed to conventional pianos which may go out of tune even after one playing.

Therefore, it is the general object of this invention to avoid the foregoing and other difficulties of the prior art practices and to achieve the results discussed above by the provision of a new and improved piano utilizing electronic tone generation techniques.

A further object of this invention is the provision of'a new and improved electronic piano capable of producing musical tones directly frorn the piano action by electronic components substituted for the standard strings and sounding board.

A still further object of this invention is the provision of a new and better electronic piano which utilizes a velocity sensitive transducer operative from the felt hammer of a piano action to produce a piano-type tone normally associated with the particular key being struck.

Another object of this invention is to produce a new, better and lighter weight piano which incorporates all of the features of tone variation possible in conventional pianos. I i

Still another object is the provision of a new and better piano which requires tuning only at infrequent intervals by the utilization of electronic sound producing components.

A further object of this invention is to provide an electronic tone generator capable of producing a piano-type tone in response to a velocity sensitive key action and/ or to produce an organ-like sound of sustained amplitude when operated from an organ-type key contact arrangement.

Other objects will appear hereinafter.

For the purpose of illustrating the invention, there is shown in the drawings a form which is presently preferred; it being understood, however, that this invention is not limited to the precise arrangements and instrumentalities shown.

In FIGURE 1, there is shown a side view of a standard piano action incorporated in the piano of the present invention.

FIGURE 2 is a schematic showing of the electronic means for-producing the piano tone associated with the key of FIGURE 1.

In FIGURE 1, there is shown a portion of the electronic piano and/ or organ tone generator 10 of the present invention. The tone generator 10 includes a grand piano action 12 having a key 14 mounted on a key frame 16 for pivotal movement about a balance rail 18. The balance rail 18 has an upstanding balance key pin 20 extendingthrough a hole provided in the key 14. The key frame 16 has a pair of cushions 22 and 24 associated with each end of the key 14 to insure a smooth limit stop for the movement of the key 14. The piano action 12 is intended to transmit downward movement of the key 14 into upward movement of the hammer 26 which is attached to a suitable hammer shank 28 pivotally secured to a frame 30. The hammer shank 28 rests on a hammer rest 32.

The hammer shank 28 has a hammer shank knuckle 34 associated therewith resting on a suitable jack or grand fly 36.

The key 14 has a capstan screw 38 integral therewith and utilized to transmit rotative movement to a suitable support 40 pivoted about the frame 30. The jack 36 is pivoted about the other end of the support 40' so that upward movement of screw 38 causes the jack 36 to force the knuckle 34 of the hammer shank 28 upwardly and provide upward movement of the hammer 26. The jack 36 is guided in this movement by a balancer 42 pivotally mounted about a top flange of support 40. The jack 36 is further returned to its initial position by a suitable repetition spring 44 and the balancer 42 is returned to its initial position by a repetition spring 46 to thus aid in Patented Apr. 26, 1966' 3 biasing the key 14 to its released position shown in FIGURE 1.

The key 14 has a hammer check 48 at the end thereof to cushion the return of the hammer 26 after the completion of a stroke.

All of the elements discussed above form a portion of the grand piano action 12 and are conventional. Any other type of piano action, such as an upright action, which would be desired by the designer could be utilized in place of the grand piano action 12. The piano action in itself does not form any portion of the present invention.

The hammer 26 has at its striking end a cushion 50 surrounding a core 52. The core 52 is adapted to enter a suitable opening 54 in a coil 56 mounted above the hammer 26. When the key 14 is struck by the player, the core 52 will enter the opening 54 in the coil 56. The coil 56 acts as a transducer for the electronic piano tone generator 58 associated with the patricular piano action 1'2 discussed previously. The coil 56 transduces the movement of the hammer 26 directly into an electrical signal proportional to the velocity thereof.

As stated earlier, the importance of the piano rests upon its powerful and finely graduated tone and its convenience for the production of concerted music. Thus, the electronic piano tone generator 58 must be capable of utilization with a piano action of the general type to control one or more electronic oscillators. Further, means must be included in the tone generator to control the amplitude, the decay characteristics, and the pulse length of the oscillator to vary the tones produced thereby.

-The circuitry forming the piano tone generator 58 can be divided into two separate circuits 60 and 62 which are utilized to simulate the sound generating from a two string tone. In a conventional piano, the strings are steel wires of graduated thickness and length, the larger being made heavier by being wound with copper wire. For each of the extreme upper and lower tones, only one wire is provided, but for most of the others, there are two or three wires which are tuned in unison and placed so that they will be simultaneously struck by a single hammer. The tone generator 58 is associated with a key utilized to produce one of the middle. notes on the piano scale utilizing two strings in unison.

The components of the circuit 58 will be discussed in an integrated discussion of their operation. The coil 56 has one terminal connected to a source of supply Eb and its other terminal to the base terminals 64 and 164 of transistors 66 and 166 respectively. The core 52 is a permanent magnet attached to the hammer 26 which will enter the coil 56 with a velocity that will be proportional to the velocity with which the key 14 is struck. Since the induced voltage in a coil is determined by the number of flux lines cut per unit time, the voltage developed across the coil 56 will be proportional to the velocity of the struck piano key within limits. The coil 56 voltage is applied between the base 64 and the emitter 68 of transistor 66 causing it to conduct and resulting in the charging of capacitor '70 from source Eb. The charge on capacitor 70 causes transistor 72 to conduct and, in so doing, applies the voltage source Eb to a Hartley oscillator 74. The oscillator 74 includes a transistor 76 having a split inductance 78 utilized to tune the collector circuit of the transistor 76.

The conductivity of transistor 72 varies with the charge on capacitor 70 or, in other words, with the voltage induced in the coil 56. The oscillator 74 operates in a manner whereby the output will be a sine wave whose amplitude will be approximately proportional to the input voltage. The output of the Hartley oscillator 74 is applied through a wave shaping circuit 80 to the audio output and loudspeaker means 82. The wave shaping circuit 80 is a standard means of imparting a string quality to the amplified and transduced sound.

In a conventional piano, there is normally provided a damper which will damp the string after the key is returned to its initial position. This damping is achieved in the piano tone generator 58 of the present invention by utilizing a switch 84 located belowthe key 14. The contacts of switch 84 are opened when the key is struck and are closed when the key is in its normal position. After a key is struck and the capacitor 70 has charged as discussed previously, it discharges through a high resistance resistor 85 and transistor 72 so that it has a long time delay as would be normal when striking an undamped key on a piano. However, when the key is released and returns to its up or closed position, the capacitor 70 can discharge through diode 86, low resistance resistor 88 and the now-closed contacts of switch 84 to ground. The capacitor 70 voltage will thus be quickly reduced to zero voltage and the oscillator 74 will be stopped.

A second set of contacts 90 are connected in series with the contact 84 and every other contact 84 associated with each key of a piano to perform the function of the sustaining pedal on the piano. The sustaining pedal on a conventional piano prevents the dampers associated with every key from dampening the vibration of their associated strings. The sustaining switch 90 performs this function by allowing the voltage on capacitor 70 to continue to decay through the resistor 85 and transistor 72 by opening the circuit betweeen resistor 88 and ground. Thus, the tone produced by the key 14 will decay for a period of time after the key has been released in the same manner as a conventional piano whose sustaining pedal has been pressed.

The portion 62 of the tone generator 58 has substantially the same components as the portion 60 as it is merely intended to reproduce a string exactly similar to the string reproduced by the portion 60 in the same manner as a two stringed tone on a conventional piano. The portion 62 will be controlled in the same manner and simultaneously with the portion 60, and will provide the additional amplitude plus any possible interference efiects which result from slight differences between the two identical circuits. The portion 62 has been noted with numerals exactly one hundred more than its associated components in portion 60. For example, an oscillator 174 is provided exactly similar to the oscillator 74 discussed previously.

In a complete piano built in accordance with the principles of the present invention, each key will be associated with a similar set of components as described heretofore, but tuned to the required frequency. The sustaining contacts 90 would connect to a common bus 200 associated with all of the contacts similar to contact-84 associated with each key of the piano. Isolating diodes would be provided between each key to prevent interaction of the oscillators. A mechanical arrangement would be provided so that the sustaining pedal contacts 90 would be actuated by a foot pedal. Further, the piano could be designed to have a separate pedal which would only sustain the bass notes rather than all of the notes. Additionally, a sostenuto pedal could insure the sustaining of a tone only after the particular key had been struck. Still further, a soft pedal could be provided to act as an electronic substitute for the conventional soft pedal by switching out one portion of each tone generator having more than one oscillator. This would lessen the amplitude of the output signal of the tone generators in the same manner as is now done on conventional pianos. In the alternative, the soft pedal could proportionately lessen the amplitude of the output signals of the tone generators.

The tone generator 58 can additionally be utilized with a separate set of organ keys for producing an organlike sound of sustained amplitude either separately or in combination with the piano discussed above. The organ keyboard has been shown representatively by the organ key 92. The organ key 92 rotates about a fulcrum 94 to open and close its associated contacts 96;

The key 92 is spring loaded to an open position by a conductive spring 98 connected to the voltage source Eb. Upon pressing the key 92, contacts 96 are closed completing a circuit from the voltage source Eb through a resistor 100, capacitor 102, wave shaping circuit to the input of transistor 176 in oscillator 174.

In the interest of economy, the organ contacts could be placed below the piano keys 14 and suitable switches arranged in the circuit to cut out the piano signal transducer while connecting the organ contact to the oscillators and vice versa.

The present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof and, accordingly, reference should be made to the appended claims, rather than to the foregoing specification as indicating the scope of the invention.

It is claimed:

1. An electronic piano comprising a key operated action, velocity sensitive transducer means for directly transducing the velocity of a struck key into an electric signal proportional thereto, a tuned circuit oscillator, and means for applying the electric signal to said tuned circuit oscillator to control the output of said tuned circuit oscillator, and audio output means connected to said tuned circuit oscillator.

2. The electronic piano of claim 1 wherein said action includes a hammer and means for controlling the movement of said hammer by said key, a core element on said hammer, said velocity sensitive transducer means including a coil, said core and coil being positioned to vary the inductance of said coil in accordance with the velocity of said hammer.

3. The electronic piano of claim 1 wherein said tuned circuit oscillator includes means for producing a characteristic tone signal whose amplitude varies with the input signal to said oscillator, an oscillator input means for connecting said oscillator responsive to said velocity sensitive transducer means.

4. The electronic piano of claim 3 wherein said velocity sensitive transducer means includes a transducer operative to provide a signal proportional to the velocity of said key, signal storage means energized by said transducer, said signal storage means being operative to store said transducer signal and transmit said transducer signal to said oscillator for a predetermined period of time.

5. The electronic piano of claim 3 including a second oscillator similar to said first-mentioned oscillator, said second oscillator being responsive to said velocity sensitive transducer means signal.

6. The electronic piano of claim 3 wherein said oscillator includes means for producing a sine wave output varying in amplitude in accordance with said velocity sensitive transducer means signal, said audio output means additionally including a wave shaping circuit, said wave shaping circuit including means to modify said oscillator sine wave output, means connecting a speaker to said wave shaping circuit, said wave shaping circuit including means to transmit a string-like tone signal to said speaker from said oscillator.

7. An electronic piano comprising a key, electronic transducer means for producing a signal in accordance with the force of the striking of said key, an electronic tone generator for producing a tone signal corresponding similar, each of said tone producing circuits including means for producing a tone signal-corresponding to said key, means for varying the amplitude of said tone signals produced by said tone producing circuits in accordance with the amplitude of said transducer means signal, and means for applying said tone circuit tone signals simultaneously to said audio output means for producing a composite tone generator tone signal corresponding to said key.

9. The electronic piano of claim 7 including first sustaining means for sustaining the output of said electronic tone generator for a period of time after the release of said key by a player.

10. The electronic piano of claim 9 including a second sustaining means, said second sustaining means being operative to sustain the tone signal from said tone generator tfor a period of time greater than that of said first sustaining means.

11. The electronic piano of claim 10 wherein said key is biased to a released position, and key position sensing means for sustaining said tone signal for the same period of time as said second sustaining means so long as said key is in a depressed position.

12. The electronic piano of claim 11 wherein said key position sensing means is a switch operative by said key.

13. Electronic musical apparatus comprising key means, electronic transducer means for producing a signal in accordance with the force of the striking of said key, an electronic tone generator for producing a tone signal corresponding to said key means and for varying said tone signal amplitude in accordance with the amplitude of said transducer means signal, audio output means for producing an audio output in accordance with the output of said electronic tone generator, key position sensing means, said key position sensing means being operative in accordance with the depression of said key means to produce an output signal, said electronic tone generator being additionally sensitive to said position sensing means output signal to produce a tone signal corresponding to said key means, said last-mentioned tone signal being of a sustained amplitude.

14. The musical apparatus of claim 13 wherein said key means comprises a key operated action, said transducer means being associated with said key operated action for producing a signal in accordance with the force of the striking of said action key, said key means additionally including a second key, said position sensingmeans including contacts associated with said second key.

15. An electronic piano comprising a key operated, velocity sensitive transducer means for directly transducing the velocity of a struck key into an electric signal proportional thereto, a core element associated therewith, said velocity sensitive transducer means including a coil, means to move said core to vary the inductance of said coil in accordance with the velocity of said key, means for applying the eleotric signal to an electronic oscillator, and audio output means for producing an audio signal in accordance with the output of said oscillator.

16. An electronic musical apparatus comprising a key, an action responsive to a struck key, said action including a hammer and means to move said hammer in a predetermined path when said key is struck, a core element of magnetizable material mounted on said hammer, a velocity sensitive transducer including a coil aligned in the path Olf movement of said core element, whereby said core element may be moved adjacent said coil to change its inductance, electronic means responsive to changes in the inductance of said coil to develop a tone generator triggering signal, a tone signal generator responsive to said triggering signal to produce an output electric signal, said tone signal generator including an oscillator and a wave shaping circuit, and audio output means connected to said Wave shaping circuit for producing an audio signal in accordance with said tone signal.

(References on following page) References Cited by the Examiner 2,357,191 8/1944 Hanert 84-1.2 X V UNITED STATES PATENTS 3,0 8, 5 6/1962 PG'CGI'SOH 84-1.26

1,318,977 10/1919 Darley 84-11 v 1,979,633 11/1934 Miessner 84-11 ARTHUR GAUSS 2,296,125 9/1942 Traub 84-1.27

I. C. EDELLgAssistant Examiner.

Disclaimer 3,248,470.-Jerome Markowitz, Allentown, M z'lton F. Nelson, Macun ie, and Edwin H. Strain, Allentown, Pa. ELECTRONIC PIANO H VING MEANS RESPONSIVE TO THE VELOCITY OF THE ACTION. Patent dated Apr. 26, 1966. Disclaimer filed June 2, 1969, by the assignee, Allen OTgan Company.

Hereby enters this disclaimer to claims 7 and 13 of said patent.

[Oflicz'al Gazette July 8, 1.969.] 

1. AN ELECTRONIC PIANO COMPRISING A KEY OPERATED ACTION, VELOCITY SENSITIVE TRANSDUCER MEANS FOR DIRECTLY TRANSDUCING THE VELOCITY OF A STRUCK KEY INTO AN ELECTRIC SIGNAL PROPORTIONAL THERETO, A TUNED CIRCUIT OSCILLATOR, AND MEANS FOR APPLYING THE ELECTRIC SIGNAL TO SAID TUNED CIRCUIT OSCILLATOR TO CONTROL THE OUTPUT OF SAID TUNED CIRCUIT OSCILLATOR, AND AUDIO OUTPUT MEANS CONNECTED TO SAID TUNED CIRCUIT OSCILLATOR. 